Download Chapter 4 Section 1: Living Things Inherit Traits in Patters

Chapter 4 Section 1: Living Things
Inherit Traits in Patterns
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Objectives:
1. I can explain how traits are passed from
parent to offspring.
2. I can describe how genes are distributed in
sexual reproduction.
3. I can understand that some traits are
dominant and others are recessive.
4. I can design a model to determine genotype
and phenotype.
Parents and Offspring are Similar
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Everyone has a unique combination of
characteristics.
These characteristics are also known as
traits.
Many of your traits may resemble your
parents traits.
Examples: Hair color, Eye Color, Blood Type
These traits or characteristics are called
inherited traits.
Parents and Offspring are Similar
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The inheritance of traits happens through
sexual reproduction
A cell containing genetic information from
the mother and a cell containing genetic
information from the father combine into a
completely new cell.
That cell then becomes the offspring.
Parents and Offspring are Similar
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Some traits are acquired, not inherited.
An acquired trait is one that is developed
during your life.
Learned behaviors are one type of acquired
trait.
Examples: Reading, Writing, Riding a Bike
Genes are on Chromosome Pairs
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A gene is a unit of heredity that occupies a
specific location on a chromosome and codes
for a particular product.
Heredity is the passing of genes from parents
to offspring.
These genes code for the expression of traits
Cells contain pairs of chromosomes, with one
chromosome coming from each of the parents.
Chromosome pairs are called homologs.
Genes are on Chromosome Pairs
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The various form of the same gene are called
alleles.
Ex.–The gene that determines height is located at site
A on a pair of homologs. Though both homologs have
the gene for height at site A, the genes may not be
indentical.
Each species has a characteristic number of
chromosomes.
Humans have 23 pairs, for a total of 46 Chrom.
The 23rd pair of chomosomes in humans is the
sex(gender) chromosome
Genes are on Chromosome Pairs
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In humans, the sex chromosomes are called
the X-chromosome and the Y-chromosome
A human female has 2 X-chromosomes, while a
human male has 1 X-chromosome and 1 Ychromosome.
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Gregor Mendel Made Some Important
Discoveries About Heredity
The first major experiments investigating
heredity were performed by a monk named
Gregor Mendel
Mendel worked with 7 different traits
Mendel realized that each plant must have 2
factors for each possible trait, 1 factor from
each parent
Some factors (traits) could be masked, such as
dwarf height.
Phenotype and Genotype
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An organisms phenotype describes the actual
characteristics that can be observed.
Ex. – Eye color, height, feet size, etc.
Genotype is the name for the genes an
organism has.
Dominant and Recessive Alleles
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A dominant allele is one that is expressed in
the phenotype even if only one copy is present
in the genotype.
A recessive allele is one that is expressed in the
phenotype only when two copies are present in
the genotype.
If a dominant allele is paired with a recessive
allele, then the dominant trait will appear in the
phenotype.